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IP verification on email

Hello,

I have an issue with some companies that are doing a reverse look up on email leaving my org. If they can't find my external IP they will tag the email as SPAM.

How does this process work and what exactly are these reverse lookups looking for?

I send directly out to the internet from my exchange server which is in the inside network.

Thanks,.
Juan

Sembee

You know how DNS works?

Enter a name (www.domain.com) and the DNS system finds that www.domain.com is on the server with the IP address 10.10.10.10.

What reverse DNS does is lookup what is on 10.10.10.10.
Depending on how strict they are will depend on whether they are just looking for something on that address, or whether it matches what your server is announcing itself as.

Therefore if your server announces to the world as server1.domain.local but the IP address that it is coming from is mail.domain.com then that can cause problems.

You can use the tools at dnsstuff.com to see what the Internet thinks is your reverse lookup on your IP address.

How do you fix?
Your ISP needs to resolve the reverse DNS lookup, as they own the IP address. Ask them to put a reverse DNS on to your IP address.

To get Exchange to announce itself as the name that it is known as requires a change to the SMTP settings on Exchange. You haven't said which version of Exchange you are using, so I cannot really tell you where that is.

Does that help?

Simon.

jibarra

ASKER

Although not an expert, I know how DNS works. I am using Exchange 2003 on windows server 20003.
Is it a good practice to allow this reverse look up as not all domains have this problem?
Thanks,
Juan

ASKER CERTIFIED SOLUTION

Sembee

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